The field of the invention is that of condition-responsive members and devices, and the invention relates more particularly to condition-responsive members and devices such as dished metal members adapted to move between spaced dispositions or the like such as between original and inverted dished configurations, preferably with snap-action, in response to occurrence of predetermined bias, force, deflection, temperature or pressure conditions or the like.
Many different types of condition-responsive control devices such as thermostats, motor protectors mechanical switches and pressure switches and the like use condition-responsive dished metal members or other bistable or movable members or the like to actuate the devices to move between control positions or change applied forces or the like in response to change in conditions. Dished metal members for example are commonly arranged to move between original and inverted dished configurations with snap action in response to occurrence of a selected temperature, force, or pressure condition or the like and are typically arranged in a condition-responsive device to engage and move a control element of the device to perform a selected control function when the snap-acting member movement occurs. Frequently the condition-responsive member is adapted to move between its two spaced dispositions in response to occurrence of a first condition and then to return to its previous configuration, typically with snap-action, on occurrence of a second condition. In the condition-responsive devices it is usually important that the condition-responsive member move in response to the occurrence of precisely predetermined temperature or pressure conditions or the like and the manufacture and processing of dished metal members in attempting to make such members in an accurate and economical manner is well developed and well known and does result in production of useful and reliable condition-responsive devices in many respects. Frequently, however, the manufacturing tolerances encountered during manufacture of the condition-responsive members and then during their assembly in condition-responsive devices are such that, particularly where the members and devices are manufactured and assembled using large volume or automated manufacturing methods, a substantial number of the members and devices as manufactured are found to be out of tolerance. The absence of the desired precision is in some respects due to difficulties in manufacturing the control members with desired accuracy and in part due to difficulty in arranging the control members in control devices in such a way as to be consistently subjected to the same forces within the assembled devices. That is, it is found that, when the condition-responsive members are tested after being formed, substantial numbers of the members will display condition-response properties which are out of tolerance so that high rejection rates are commonly encountered in member manufacture. Sometimes the rejected members are subjected to being formed again in attempting to bring the members into tolerance but the rehandling required for such re-forming is often not economical. Most important, when the members are mounted in condition-responsive devices, the members are commonly engaged by control elements of the devices which apply forces to the members and which change the condition-responsive properties of the members in the device. As a result, when the devices are tested after assembly, they frequently display condition-response properties which are out of tolerance so that high rejection rates are again encountered in device manufacture. Again the rejected devices are commonly adjusted by means of adjusting screws, bending of member supports, etc., to calibrate the devices but again device calibration is also inconvenient and expensive. In the case of rejection of devices, the rejection results in loss of the full cost of the assembled device.